The present invention relates to a supply network component for a supply network for a network medium. In particular, the present invention relates to an energy supply network for supplying more consumers with electrical energy. In particular, the supply network component can in this case be an energy store, an energy converter or an energy source or else an energy consumer.
Rechargeable batteries as energy stores and as energy sources in voltage networks for supplying consumers with electrical energy are generally known. Conventional energy stores include alkaline batteries, for example, of standardized housing sizes such as, for instance, Micro(AAA), Mignon(AA), Baby(C), Mono(D), which in each case provide a voltage of 1.5 volts, or else block batteries having a voltage of 9 volts or flat-pack batteries having a voltage of 4.5 volts. There likewise exists rechargeable variants of these energy stores on the basis of nickel/cadium (NiCd) or nickel/metal hybrid (NiMh) or on the basis of lithium.
Such batteries can then be adapted to a specific application with regard to the operating voltage by series connection. In the case of known automobile and motorcycle batteries as well, for the respective connections and designs there are some standardized forms which allow a user to choose between different manufacturers and qualities. These batteries also allow the user or the specialist himself/herself to carry out a battery change. A designer and developer in the case of these batteries can build on a global standard which allows service support all around the world. For cylindrical rechargeable cells there is a large choice of chargers, charging stations and applications.
This is not the case, however, for rechargeable lithium batteries. In most cases, the batteries have to be specifically adapted to the application and to the charging system. On account of the increased safety requirements and the hazard potential for the user in the case of fire, this type of battery is no longer simple and uncomplicated in terms of handling. Parallel and/or series connection without complex controls is not possible. Limit values predefined by a manufacturer often have to be taken into account. Any overload can lead to the failure of a cell or even to uncontrolled fires. Consequently, it is customary nowadays to design and construct for each application a dedicated adapted battery system with an adapted charging system.
The requirements made of the quality of an individual battery increases in the case of relatively large battery arrangements and correspondingly high battery voltages, since, in the case of a series interconnection of batteries or cells, each individual cell must be functional. If a cell can no longer transport a current, is fully charged or discharged, the entire arrangement has to be switched off. Therefore, such a battery arrangement is always defined by the weakest and strongest cells. Thus, the quality requirements made of the individual cells are extremely stringent. The battery lifetime is intended to be correspondingly long. In the case of laptops and cellular phones, the lifetime of the device is expected to be two years. A technology is then generally deemed to be obsolete. This means a reasonable lifecycle for the battery or cell used. Moreover, the value share of the battery is not dominant; the failure thereof and the procurement of replacement parts are noncritical. The same applies to lead-acid batteries in motorcycles and automobiles. Multiple exchange during the lifetime is routine practice here. The automobile battery is statistically the most frequent cause of breakdowns in the passenger vehicle and motorcycle sectors. Similar approaches for the lifetime are unacceptable for electrical mobility.
In any cell pack it is necessary to keep each individual cell in the same state of charge. In the case of lead-acid, NiCd and NiMh this is produced by overcharging the battery, which results in heating of the full cells, but is possible within limits. This is not allowed for lithium-ion cells, or that is to say that some types of cells, as soon as they are fully charged, acquire high impedance and no longer take up current. Therefore, it is important to match the cells among one another by means of additional circuits. In order to obtain a harmoniously cooperating cell pack, the production process usually involves checking and sorting each individual cell, in order to use only cells of identical type in a cell pack. In order that uniform aging arises in a pack, it is important to keep all the cells at the same temperature level, which is difficult to achieve in the case of large arrangements or distributed batteries in a vehicle.
Usually, within a cell pack, if there are individual defective cells, they can be changed mechanically only with difficulty or not at all. Furthermore, it is normally found that, if old and new cells are connected in series, the pack reacts homogeneously only for a short time. As a result, repair by changing individual defective cells of interconnected packs is not recommendable and is therefore not practiced either.
Especially for mobile applications and vehicles it is of interest to meet the user's requirements by means of the chemical composition and the internal construction of the battery. Price, continuous and peak power, energy content, safety, charging time, lifetime and use temperature can be shifted by means of the chemical composition or variation of the stipulated limit values.
In the case of electric bicycles, in the meantime there are many combinations of chargers and batteries which function only as a closed unit. In this case, a direct-current connection is often used as plug connector. In this case, it is not possible to prevent chargers for e.g. 36-volt batteries from being connected to 24-volt batteries.
The end of the lifetime of a battery is defined nowadays such that it is reached as soon as the battery has only a residual capacity of approximately 70-80% of its original capacity. In this case, the possible charging and discharging capacity of a battery decreases linearly as the number of cycles increases. It can thus happen that a battery having a residual capacity of 80% is to be disposed of. Secondary further use of these batteries is desirable.
In the case of electric vehicles, the proportion of costs for batteries is disproportionately high. Therefore, it would be desirable to have only the storage capacity that is actually required. Refilling or rapid exchange of the batteries is also a desirable criterion. Especially in the case of cars and buses there are models which enable complete exchange of the battery block. However, the formation of a standard is an undertaking that is difficult to realize, owing to the different battery geometries and the different sizes.
The so-called “EnergyBus” standard on the basis of the standard of CANopen (Controller Area Network) forms the basis for the control and communication of intelligent electricity network components in the mobile application. Load regulation is distributed among a plurality of bus subscribers and it is absolutely necessary to define an unambiguous master for the energy management. The number of batteries is limited here. The data connection is created in bus form as a CAN bus. The routing of the electricity cannot be comprehended unambiguously.
A combination of batteries having different capacities is described in the document WO 2012 009281 A1. The document WO 2012 008244 A1 discloses a use of two rechargeable batteries connected in parallel. Furthermore, the document WO 2011 163306 A2 discloses a possibilities for balancing large electric vehicle batteries. The document EP 2 343 752 A3 discloses a battery having a cylindrical housing form. The document WO 2011 121755 A1 discloses the possibility of employing used rechargeable battery cells by measuring and combining new appropriate cell pairings. The document WO 2011 060096 A3 proposes an automatic parallelization of battery packs. The document DE 10 2008 050437 A1 discloses a scalable automobile battery. The document DE 10 2006 055883 B4 discloses a modular system for energy converters and energy stores. The document DE 19615943 A1 discloses a solar system composed of standard parts. The document DE 10 2010 027854 A1 discloses alternate charging and discharging of rechargeable batteries. The document DE 10 2010 023049 A1 discloses a modular system for batteries for optimized maintenance tasks. The document US 2011 0163603 A1 discloses a hybrid, centrally controlled energy supply. The document DE 10 2006 043831 A1 discloses a battery system composed of partial batteries connected via bidirectional direct current converters. The document DE 10 2006 047654 A1 discloses an automatic battery changing station for cars.
The present-day large multi-cell battery systems exhibit a number of fundamental problems. As a result of a high number of cells, the probability of a failure increases linearly with the number of cells connected in series. In most cases of a cell defect, the entire battery unit has to be replaced, which results in high costs.
In the case of the battery concepts such as are currently used in the case of cars, a high operating voltage arises which has to be correspondingly safeguarded by means of appropriate insulation monitorings even in the case of an accident. Repairs on batteries are normally not possible even for specialist workshops. The customer normally has to enter into a supply relationship for the energy store with the application manufacturer and cannot have recourse to a second alternative. As a result, no competition can arise. Especially in the case of lithium, every product or vehicle gives rise to an independent battery design which cannot readily be scaled and applied to other applications. The development time and tests often have to be undergone again in the event of design changes. Battery exchange stations can arise appropriately only for individual vehicle and battery types.
The potential risk of danger increases with the size of the battery pack. Lithium batteries are always deemed to be hazardous material. There are currently three limits in Germany. Everything below 100 Wh is transportable without any problems even in aircraft. Lithium batteries including packaging which weigh more than 5 kg are not permitted to be transported together with persons in aircraft. Batteries above 35 kg cannot be transported as air freight.
In most applications, the charger and the battery form an inseparable combination. That is to say that the limit values for the charge and the regulation thereof are implemented by the charger. If confusion arises here between this pairing, uncontrolled overcharging often results in fires that are difficult to extinguish on account of the lithium.
The required mechanical stability of a battery pack correspondingly increases with increasing size and is not easily manageable in accident situations.
In the case of an application with fixedly installed batteries, a period of time of up to three years can elapse between the production of the device and the first use by the customer. In the case of most battery systems, this means failure as a result of deep discharge. Consequently, charging has to be carried out regularly during storage. It would therefore be advantageous for the application and the batteries to be stored and supplied separately, in order to be able to supervise the storage time of the batteries.
A large number of manufacturers that are concerned with the production of lithium cells and assemble the latter, and also users and transport companies are exposed to the constant hazard of a fire. In this context, vehicle manufacturers, warehouses, garages, ferries, ships and aircraft have also been damaged or destroyed in the past. Battery packs that have mechanical damage prove to be extremely hazardous in this context. In the case of lithium cells, a fire can suddenly break out even after weeks. Particularly tiny short circuits within individual cells owing to contaminants that arose during production initiate fires here even after years of use. In the case of necessary recall actions it is often not possible to trace where the individual batteries have gone.
Large battery packs can be constructed nowadays only with homogeneously identical measured individual cells. The quality demands for the individual cell and a homogeneous temperature distribution in the pack are the basis for long-lived operation. Solutions for exchanging individual cells or partial regions do not exist.